Kluge: The Haphazard Construction of the Human Mind (Houghton Mifflin; 2008)

There's no doubt that recursion — or something like it— is central to human language. The fact that we can put together one small bit of structure {the man) with another {who went up the hill) to form a more complex bit of structure {the man who went up the hill) allows us to create arbitrarily complex sentences with terrific precision ( The man with the gun is the man who went up the hill, not the man who

* Although I have long been a huge fan of Chomsky's contributions to linguistics, I have serious reservations about this particular line of work. I'm not sure that elegance really works in physics (see Lee Smolin's recent book The Trouble with Physics), and in any case, what works for physics may well not work for linguistics. Linguistics, after all, is a property of biology — the biology of the human brain — and as the late Francis Crick once put it, "In physics, they have laws; in biology, we have gadgets." So far as we know, the laws of physics have never changed, from the moment of the big bang onward, whereas the details of biology are constantly in flux, evolving as climates, predators, and resources, change. As we have seen so many times, evolution is often more about alighting on something that happens to work than what might in principle work best or most elegantly; it would be surprising if language, among evolution's most recent innovations, was any different.

drove the getaway car). Chomsky and his colleagues even have suggested that recursion might be "the only uniquely human component of the faculty of language."

A number of scholars have been highly critical of that radical idea. Steven Pinker and the linguist Ray Jackendoff have argued that recursion might actually be found in other aspects of the mind (such as the process by which we recognize complex objects as being composed of recognizable subparts). The primatologist David Premack, meanwhile, has suggested that although recursion is a hallmark of human language, it is scarcely the only thing separating human language from other forms of communication. As Premack has noted, it's not as if chimpanzees can speak an otherwise humanlike language that lacks recursion (which might consist of language minus complexities such as embedded clauses).* I'd like to go even further, though, and take what we've learned about the nature of evolution and humans to turn the whole argument on its head.

The sticking point is what linguists call syntactic trees, diagrams like this:

*In a hypothetical recursion-free language, you might, for example, be able to say "Give me the fruit" and "The fruit is on the tree," but not the more complex expression "Give me the fruit that is hanging on the tree that is missing a branch." The words "that is hanging on the tree that is missing a branch" represent an embedded clause itself containing an embedded clause.

Small elements can be combined to form larger elements, which in turn can be combined into still larger elements. There's no problem in principle with building such things — computers use trees, for example, in representing the directory, or "folder" structures, on a hard drive.